Testosterone/SHBG
The testosterone/SHBG ratio (free androgen index) estimates how much testosterone is free for the body to use.
The testosterone/SHBG ratio (free androgen index) estimates how much testosterone is free for the body to use. A large part of testosterone in the blood is bound to the protein SHBG, so total testosterone alone does not show how much is available. The ratio is calculated from total testosterone and SHBG. Retesting shows how it changes over time.
Anything that changes testosterone or SHBG moves the ratio. SHBG tends to rise with age, with a lot of alcohol and with the contraceptive pill, which lowers the ratio. Extra weight around the waist and high insulin levels tend to lower SHBG. Sleep, stress, training, time of day and some medicines also play a part.
Foods that help
Enough protein, healthy fats from fish, nuts, seeds and olive oil, and zinc-rich foods such as shellfish, meat, legumes and pumpkin seeds. Regular strength training and good sleep.
Foods to limit
Large amounts of alcohol, sugar and highly processed food. Long periods of very low calorie intake.
Track it through the year
One value is a snapshot. Following it up shows whether what you changed is working.
Related markers
Educational information only — not a diagnosis. Every result is checked against safe limits, and anything critical is escalated for follow-up.
See all 84 markers →